Apparatus for fixing radioactive waste

ABSTRACT

Fixing radioactive waste is disclosed in which the waste is collected as a slurry in aqueous media in a metering tank located within the nuclear facilities. Collection of waste is continued from time to time until a sufficient quantity of material to make up a full shipment to a burial ground has been collected. The slurry is then cast in shipping containers for shipment to a burial ground or the like by metering through a mixer into which fixing materials are simultaneously metered at a rate to yield the desired proportions of materials.

United States Patent 1 Murphy et al.

1 May 13, 1975 l l APPARATUS FOR FIXING RADIOACTIVE WASTE [75]Inventors: John D. Murphy, Bedford Hills;

John Pirro, Jr., Rutland; Monsey Lawrence; Stanley F. Wisla, both ofYorktown Heights, all of N.Y.

[73] Assignee: Atcor lnc., Park Mall, Peekskill,

[22] Filed: July 20, I970 [211 Appl. No.: 56,625

[52] U.S. C1 252/30Ll W [51] Int. Cl C09k 3/00 [58] Field 01' Search252/301.l R, 301.1 W

[56] References Cited UNITED STATES PATENTS 3,012,385 l2/l96l Hufft252/301.1 W 3.142648 7/1964 Lefillatre et al. 252/301.1 W 3,507,8014/1970 Kausz et al 252/301.1 W $513,100 5/1970 Stogner 252/3011 OTH ERPUBLICATIONS Stoller et al., Reactor Handbook, Vol. 11, Fuel Reprossing,1961, p. 498

Lawroski et al., Reactor Fuel Processing, Vol. 8, No. 3, 1965, pp.172473, USAEC-Argonne National Lab.

Flagg, Chemical Processing of Reactor Fuels. Academic Press, New York,1961, p. 467.

Martin et al., Chemical Processing of Nuclear Fuels, Academic Press. NewYork, 1958, p. 198.

Primary E.raminerBenjamin R. Padgett Assistant Examiner-R. L. Tate [57]ABSTRACT 3 Claims, 4 Drawing Figures SLURRY PUM P INVENTORS JOHND.MURPHY JOHN P|RRO,JR. LAWRENCE RUTLAND STANLEY F.W|SLA 29 J0 SHIPPINGCONTAINER AUGER FEED HOPPER b a O BY I %smgMazl Mei @6141 ATTORNEYSAPPARATUS FOR FIXING RADIOACTIVE WASTE This invention relates todisposal of radioactive waste and, in particular, to such disposal byfixing the waste for shipment to a burial ground or the like.

BACKGROUND OF THE lNVENTlON Radioactive wastes accumulate in nuclearpower generating stations and are, for example, contaminated bead ionexchange resin, powdered resin, filter aid, filter precoat andevaporator bottoms which are contaminated typically with corrosion andfission products.

The present practice in disposal of radioactive wastes is to mix thewastes with cement and water, if required, and to cast these in drumsfor shipment to a burial ground. Fixing is required by most burialgrounds in order that the radioactive waste not be available to theenvironment and is also desirable, as it prevents spread of radioactivematerial which might occur incidental to an accident in shipment. Thepresent practice of fixing radioactive wastes at a nuclear facility iscumbersome and presents potential contamination problems.

GENERAL SUMMARY OF THE INVENTION This invention is generally applicableto the disposal of any radioactive wastes which can be slurried in anaqueous medium and has for its general purpose fixing of such wastes ona production line basis avoiding the difficulties of atmosphericcontamination and nonuniform mixture characterizing prior fixingmethods.

In accordance with this invention radioactive wastes are collected fromtime to time, and slurried in an aqueous medium in a metering tank whichis contained in a shielded enclosure. The metering tank is adapted tometer the collected slurry, when required, through a mixer which is alsoconnected simultaneously to receive cement or other fixing materials inmetered quantities proportionate to the metering rate of the slurry. Themixer is shielded and arranged continuously to discharge metered andmixed fixing material and slurry into a shipping container for shipmentto a burial ground when the mixture has set.

Ordinarily in accordance with this invention the furing process iscarried out only when a sufficient quantity of radioactive waste hasbeen collected to constitute a suitable quantity for shipment to aburial ground. This quantity may involve one or several shipping casksor other containers and the fixing process is carried out continuouslyuntil the desired number of casks have been charged. Thus expensiveshipping casks are tied up at the particular plant only for that timenecessary for the fixing operation and need not be kept on hand asstorage vessels until an adequate quantity for shipment has been madeup.

Another advantage of this invention is that it is flexible in terms ofachieving the proper ratio of water to fixing material in the mixture.Thus if the radioactive wastes are in slurry fonn containing excesswater they can readily be dewatered by decanting or filtering from themetering tank prior to fixing. If they are solid wastes additional watercan be added as required. The proportions of fixing material, water andwaste materials are a function of density, shielding requirements,moisture content and ultimate disposition of the fixed waste.

For a more complete understanding of the practical application of thisinvention reference is made to the accompanying drawings in which:

FIG. 1 is a fragmentary elevation partly in section of the wasteprocessing facility of a nuclear power plant;

FIG. 2 is a plan view partly in section of the facility shown in FIG. 1;

FIG. 3 is an end view partly in section of the same facility; and

HG. 4 is a schematic diagram of certain apparatus shown in FIGS. 1, 2and 3.

Referring to the drawings the reference numeral l0 designates abuilding, housing a waste processing facility at a nuclear power plant.The waste processing facility itself includes a metering tank ll, hopperl2 and.a mixer 13. Both metering tank It and its associated equipmentand hopper l2 and its associated equipment are located on a platform 16in the processing area of the power plant such that a portable shippingcontainer, such as a movable shipping cask 14 or lCC approved drummounted, for example, on a dolly 15 can be positioned beneath platform16 to receive the contents of metering tank I] and hopper 12 throughmixer 13 which is mounted on the underside of platform l6.

Exemplary of the portable containers used in this invention are ashielded nuclear cask licensed in accordance with ABC regulations, Title10, Chapter 71, Code of Federal Regulations for large quantities" ofradioactive materials or Department of Transportation regulations forGroup B shipments or Group A or low specific activity. In addition lCCapproved single trip containers for radioactive materials, e.g.,ICC-17H, 55 gallon steel, open head, typify the drums used herein.

The processing area in building 10 is entirely enclosed in concrete,including an outside wall 17, a rear wall 18 and a ceiling 19 which areshown in the drawings. Platform 16 is mounted beneath ceiling 19 in thecomer where rear wall 18 and outside wall 17 join, and metering tank 11is positioned in such corner with hopper 12 mounted further out on theplatform. Walls 17 and 18 and ceiling 19 are of thick concrete and thusserve partially to shield tank ll. Metering tank 11 is shielded furtherby providing a thick concrete floor 20 on platform 16 beneath tank 11and by providing an outside wall 21 of thick concrete on platform l6rising to ceiling l9 and extending from outer wall 17 in front ofmetering tank 11. The shielded enclosure for metering tank 11 iscompleted by a U-shaped partition 22 and baffle 23 formed of concreteand extending across platform 16 from floor 20 to ceiling l9 and fromfront wall 21 to rear wall 18 defining a U-shaped access to servicemetering tank 11 when required. Arrangements not shown are provided forcharging metering tank It with slurried radioactive waste and water, asrequired, through ceiling l9.

Hopper I2 is located on platfonn l6 outside of the enclosure in whichmetering tank 11 is mounted and is provided with a downward, gravityfeed into an auger 24 leading to mixer 13 mounted on the underside ofplatform 16 beneath floor 20. Mixer 13 is also provided with aconnection 25 through a slurry pump 26 from the underside of meteringtank ll. Pump 26 is located in the shielded enclosure in which tank 11is housed and is provided with suitable valving to discharge directlyinto mixer 13 or to discharge into a line 27 recirculating the dischargeof slurry pump 26 to the upper end of tank 11. Mixer 13 itself, whilelocated on the un derside of platform 16, is housed in a steel shieldedcompartment 28 and is provided internally with a power driven agitatorsuch that fixing material and waste discharged from hopper l2 and tank11 into the upper end of mixer 13 feed by gravity to the lower end ofmixer 13 while being thoroughly mixed, such that they are dischargedthrough outlet 29 in a suitably mixed condition for casting.

Finally, it will be noted, referring particularly to FIG. 4 that watercan be withdrawn through a filter 30 and line 31 from tank 11 when it isdesired to dewater the contents. Also a radiation detector 32 is locatedin line 27 to measure the radioactivity of the contents duringrecirculation. An agitator 33 is also provided in metering tank 11 toprovide thoroughly mixed slurry of uniform consistency.

in operation radioactive waste is collected from time to time andslurried and delivered to metering tank 11, for example, through a line34. Spent resin in a demineralizer, for example, can be backflushed andfed as a slurry through line 34 to metering tank 11. The operation ofagitator 33 assures that the mixture is uniform without hot spots.Recirculation through line 27 enables radiation measurements to be madeto verify that the Curie capacity of the shipping cask or casks to beused is not exceeded. Radiation measurements could be made on thesurface of the metering tank alternatively.

As wastes are accumulated in tank 11, the radiation level rises to themaximum of the desired shipment. A shipping cask l4 fitted with a tankliner or ICC approved drums is then transferred and positioned, forexample, by dolly under platform 16 beneath mixer 13. At this point,with a knowledge of the volume of liquid contents in metering tank 11and of the volume of shipping cask or casks 14 and with the knowledge ofthe proportion of water to fixing materials required, excess waterpresent in the slurry in tank 11 is removed through filter 30 and line3]. On the other hand, if additional water is required, it is suppliedthrough line 35 followed by sufficient agitation utilizing agitator 33to insure a uniform mixture. Slurry pump 26 is then oper ated todischarge the contents of tank 11 into mixer 13 at a regulated rate. Atthe same time auger 24 is operated to supply fixing materials fromhopper [2 into mixer 13 in the proper proportion for the slurryintroduced from tank 11. Mixer 13 is also operated to agitate the mix sothat, as it is discharged from outlet 29 into the shipping cask, the mixis properly uniform. After cask I4 is filled it is sealed and the topsecured, and the cask is shipped to the burial site typically on a flatbed trailer. Depending on the means of transportation, one or moreshipping casks 14 may be filled during the course of the operation.

We claim:

1. A waste processing facility for preparing radioactive wastes fordisposal which includes means defining a shielded enclosure, a meteringtank positioned in said enclosure, said metering tank including meteringmeans for removing liquid contents therefrom at a metered rate andmeasuring means for measuring the radioactivity of liquid contentsthereof, mixing means for continuously receiving, mixing and dischargingfixing materials and liquids said mixing means being con nected to saidmetering means to receive the contents of said tank through saidmetering means, fixing materials feed means connected to said mixingmeans to deliver fixing materials thereto at a regulated rate, meansdefining a space in which to position a container relative to saidmixing means to receive the discharged contents therefrom.

2. A waste processing facility according to claim I which furtherincludes means for storing fixing materials adjacent said enclosuredefining means.

3. A waste processing facility according to claim I in which said meansdefining an enclosure is located on a platform in which said mixingmeans is positioned on the underside of said platform, the space beneathsaid platform thereby constituting said space in which to position acontainer.

4! l t i i

1. A WASTE PROCESSING FACILITY FOR PREPARING RADIOACTIVE WASTES FOR DISPOSAL WHICH INCLUDES MEANS DEFINING A SHIELDED ENCLOSURE, A METERING TANK POSITIONED IN SAID ENCLOSURE, SAID METERING TANK INCLUDING METERING MEANS FOR REMOVING LIQUID CONTENTS THEREFROM AT A METERED RATE AND MEASURING MEANS FOR MEASURING THE RADIOACTIVITY OF LIQUID CONTENTS THEREOF, MIXING MEANS FOR CONTINUOUSLY RECEIVING, MIXING AND DISCHARGING FIXING MATERIALS AND LIQUIDS SAID MIXING MEANS BEING CONNECTED TO SAID METERING MEANS TO RECEIVE THE CONTENTS OF SAID TANK THROUGH SAID METERING MEANS, FIXING MATERIALS FEED MEANS CONNECTED TO SAID MIXING MEANS TO DELIVER FIXING MATERIALS THERETO AT A REGULATED RATE, MEANS DEFINING A SPACE IN WHICH TO POSITION A CONTAINER RELATIVE TO SAID MIXING MEANS TO RECEIVE THE DISCHARGED CONTENTS THEREFROM.
 2. A waste processing facility according to claim 1 which further includes means for storing fixing materials adjacent said enclosure defining means.
 3. A waste processing facility according to claim 1 in which said means defining an enclosure is located on a platform in which said mixing means is positioned on the underside of said platform, the space beneath said platform thereby constituting said space in which to position a container. 